溶氧是水产养殖中重要的水质因子，因此需要精确控制。针对溶氧控制系统的时变性、非线性和滞后导致的控制难题，该研究提出了一种改进Smith模糊PID控制器，将模糊PID算法加入到改进Smith预测器中，以减少模型失配对溶氧控制系统的影响。在理论模型与实际模型匹配和不匹配的情况下进行仿真。结果显示，相较于PID控制器、模糊PID控制器和Smith模糊PID控制器，改进Smith模糊PID控制器的最大超调量明显小于其他3种控制器，平均为0.78%，并且能在最短时间内(约为371s)将溶氧浓度调整到目标值。此外，该研究将4种控制器应用于实际的溶氧控制过程进行试验验证。结果表明，改进Smith模糊PID控制器具有最佳的控制效果，控制精度和鲁棒性符合控制要求，可以胜任循环水养殖系统溶氧的精确控制。

 Dissolved oxygen, a crucial water quality factor in aquaculture, requires precise control. This study proposes a Modified Smith fuzzy PID controller to tackle the control challenges posed by the time-varying, nonlinear, and time-delay characteristics of dissolved oxygen control systems. By incorporating a fuzzy PID algorithm into a Modified Smith predictor, this approach aims to mitigate the impact of model mismatch on dissolved oxygen control. Simulations were conducted under both matched and mismatched theoretical and actual model conditions. Results indicate that compared to conventional PID, fuzzy PID, and Smith fuzzy PID controllers, the Modified Smith fuzzy PID controller exhibits significantly lower maximum overshoot (0.78% on average) and achieves target dissolved oxygen concentrations in the shortest time (approximately 371 seconds). Experimental validation in real dissolved oxygen control processes further confirms its superiority. The Modified Smith fuzzy PID controller demonstrates the best control performance, with accuracy and robustness meeting the requirements for precise dissolved oxygen control in recirculating aquaculture systems.